A lot. I have 7 structure decks (2 YU2, 1 KA2, 1 SDM, 1 JY2, 1 SD1, 1 SD2), the full japanse Master Collection 2, a lot of promos, and random cards I got as singles, and a few packets of Duelist Legacy.
Besides, my deck isn't ready right now. I'm getting some new cards for it soon, so it's got a...